Metal fume fever, also known as brass founders' ague, brass shakes, zinc shakes, galvie flu, galvo poisoning, metal dust fever, welding shivers, or Monday morning fever, is an illness primarily caused by exposure to chemicals such as zinc oxide (ZnO), aluminium oxide (Al₂O₃), or magnesium oxide (MgO) which are produced as byproducts in the fumes that result when certain metals are heated. Other common sources are fuming silver, gold, platinum, chromium (from stainless steel), nickel, arsenic, manganese, beryllium, cadmium, cobalt, lead, selenium, and zinc.

Welders are routinely exposed to the substances that cause metal fume fever from the base metal, plating, or filler. The most common form of exposure among welders occurs when welding galvanized steel, of which zinc is the primary component of the galvanization process. Galvanized metal must be thoroughly cleaned using an angle grinder or other abrasive means to remove the galvanized coating before welding or burning. Brazing and soldering can also cause metal poisoning due to exposure to lead, zinc, copper, or cadmium. In extreme cases, cadmium (present in some older silver solder alloys) can cause loss of consciousness.